1. Field of the Invention
The present invention relates to the field of electronic watch circuits and more particularly to integrated watch circuits incorporating an alarm, multiple time zone watches, and user programmable features.
2. Prior Art
Conventional integrated circuit watch counters are typically based upon series of frequency counters which are used for counting and storing time for display. Proper carries, adjustments for seconds, minutes, hours, days, months and years are made by means of gated couplings among the various counters. Typically, selected counter outputs are decoded within the circuitry and are coupled to the inputs of a comparative circuit which activates an alarm upon a selected coincidence event, such as shown and described in U.S. Pat. No. 3,946,549.
In a related patent, U.S. Pat. No. 4,063,409, directed to a Custom Watch, assigned to the same assignee of the present invention, a watch was described in which a random access memory (RAM) is coupled to and controlled by a programmable logic array (PLA) in order to keep time. This architecture allows a wide variety of different function watches and chronographs to be easily designed within a single circuit architecture without requiring the circuit architecture to be redesigned with each separate version of the integrated circuit watch. In such a watch the PLA was controlled by and hardwired to a RAM, thereby having a control sequence dictated by a custom designed master control circuit.
What is needed then is some means for permitting the programmability of control of an integrated circuit watch whose operative functions are based upon the combination of a RAM and PLA to more flexibly include user programmed control sequences and to include an alarm and multiple time zone watches without undue circuit complexity or large demands for chip space.